A Single-Layer Quad-Polarized 1-D Beam-Scanning Phased Array Antenna

This article presents a single-layer low-profile $8\times 8$ phased array antenna with quad-polarization switching and 1-D beam-scanning capability. By controlling the excitation phases of 16 ports, the array achieves switching between the left-hand/right-hand circular polarizations and horizontal/vertical linear polarizations while realizing ±30° scanning in the xoz plane. The dual-end feeding configuration of the series-fed array ensures a frequency-stable beam pointing along the y-axis direction. Through the vector projection analysis, the equivalent phase center spacing between two radiating fields when exciting both ports is identified as the key factor affecting cross-polarization levels during polarization synthesis in the upper hemisphere. A 1-to-8 equal-power divider and sequentially rotated minimum periodic subarray are implemented to suppress cross-polarization across the upper hemisphere. The fabricated array, printed on a 0.635 mm ( $0.0123\lambda _{\mathbf {0}}$ , where $\lambda _{\mathbf {0}}$ is the free-space wavelength at 5.8 GHz) substrate, achieves an active VSWR below 2.2 during ±30° beam scanning for all four polarization modes while maintaining operation within the 5.75–5.85-GHz band. Simulation and measurement results show good agreement.